Bill, I'm not Darin, but I can tell you what Faulk himself (as well as Barry Sanders) said about Spiller.
Not only is a dynamic in his running, unlike say Marshawn (or Willis in previous years) he is patient in the blocking of the run game. It's not the dancing, pit pat like 23 and 21 did, but it's because he understands every member of the line's blocking assignment and is waiting for the guy to get out there before he makes his next move.
Also, take a look at this video of him with Gruden, explaining how he fits into the Clemson offense on the play they review:
Gruden with Spiller